1. Field of the Invention
The present invention relates to animal feed additives based on a lysine fermentation broth produced by simple granulation and a process for their production.
2. Description of the Related Technology
The traditional powder form of lysine is hard to work with because it is easily shattered and has poor flow properties, causes losses of ingredients, is harmful to workers, takes up a large volume because it contains excipient or content-controlling agent, and is unsafe and inconvenient to store because of its high hygroscopicity. Concentrated, granulated lysine additives have been developed and used in order to overcome these disadvantages. Lysine is one of the most frequently-used amino acids in the animal feed industry. The most common form of L-lysine has been produced by processes of fermentation, filtering, crystallization, and dehydration in the form of L-lysine-HCl.
To explain simply the processes of production, a lysine fermentation broth is first filtered or centrifuged to remove micro-organisms. Then, L-lysine made by using an ion-exchange resin is concentrated. HCl is then added to the concentrated L-lysine in order to produce L-lysine-HCl. A product of L-lysine-HCl:2H2O is made by crystallizing L-lysine-HCl, and by dehydrating this, a product with less than about 1% of water is obtained.
This procedure has a number of shortcomings. Since the product is in the form of powder, a lot of dust is created, resulting in a loss of the product. Furthermore, the powder dust in this working environment can harm the health of workers and interfere with their work.
Filtering or centrifuging the fermentation broth in order to remove micro-organisms is one of the causes of lowering the yield. In addition, the high cost for filters or centrifuges is one of the reasons of increased cost price. Since biomass decreases in the process of filtering the fermentation broth, there is the disadvantage of decreased protein content in the product.
The use of ion-exchange resins is another defect. The high price of ion-exchange resin itself raises the cost price, and the enormous amount of wastewater from the ion-exchange and its treatment are problems. The wastewater is an important problem not only because it requires a high cost for disposal but also because enormous environmental pollution resulting from an accident can ruin the image of a company in the current atmosphere of emphasizing preservation of the environment.
A solution for these disadvantages is a graulating method. Since a graulated product may be obtained from a granulator immediately after a concentration process of a fermentation broth, the whole process may become much simpler than the method described above. Therefore, avoiding the use of expensive filters and ion-exchange resins results in a reduced cost price, decreased complexity of the whole process due to elimination of numerous filtering processes, and relatively simpler tasks for production, thereby producing products at a far lower price than the previous method.
However, the graulating-dehydration method may have a number of disadvantages. This method yields lower product content than the previous method. Contents other than lysine remain relatively higher because the filtering steps are simpler than the previous method. However, this is not a big problem. Since lysine is added in small amounts as an animal feed additive, the purity of lysine does not need to be very high. The second disadvantage is that this method may yield product contents that vary greatly. Since products are made directly from the concentrated fermentation broth, product contents are affected by the concentration of the fermentation broth. As the previous method employs many steps of filtering processes, the effect of the broth on the product contents is minimal. However, the granulating-dehydration method has a lesser number of processes. Since the contents of a fermentation broth varies significantly according to the conditions for the fermentation, it is usual for the contents to have some degree of fluctuation. Because of this, contents of pelletized products may have unreliable, varying content compositions.
Relating to the graulating, Masters, K. Spray Drying: An Introduction to Principles, Operational Practice and Applications. Chemical Process and Engineering Series: Leonard Hill Books London, 1972 states the second step of the procedure, the process of dehydration and agglomeration of yeast of the animal feed yeast process.
In addition, Japanese Laid-open publication No. 56-35962 (Apr. 8, 1981), describes the process for the production of pellets less than 1 mm in size using a fluidized bed granulator and dryer from slaked lime and a lysine concentrate.
EP 0122163A1 (Oct. 17, 1984) describes solid, stable animal feed composition which consist of 35-48% lysine, 10-15% proteins, 1-3% lactic acid, 2-8% other acids with less than 8 carbon atoms, 2-7% carbohydrates and oligosaccharides, 1-6% lipids and oil, 0.5-3% water, and 10-25% minerals. It is stated that, in making this kind of animal feeds, micro-organisms are not separated from the fermentation broth but destroyed, the broth is concentrated at 110-120° C., and the animal feeds are finally produced after drying steps such as a spray method, kneading granulation, a dry-flaking method, and azeotropic drying. It is also stated that the sugar concentration is kept between 5-15 g/l during the fermentation and it is controlled by stopping the fermentation when the concentration of remaining sugars is below 2 g/l.
EPA 0345717 (Dec. 13, 1989) relates to the production of riboflavin as an animal feed additive from a fermentation broth. Particles of certain sizes are selected to produce riboflavin granules after drying a fermentation broth in a spray method, pulverizing particles of excessive or deficient sizes, and re-circulating them. The pelletizing process of a fermentation broth by the second step of the procedure is described, and it is stated that fine particles used for the second-step granulation can be produced by drying in a spray method. 90% of the particles have a size less than 1 mm in diameter and density of 550 kg/m3.
In addition, Japanese Laid-open publication No. 62-104553 (May 15, 1987) relates to a process for the production of stable, solid nutritional additives with 50-70% of lysine hydrochloride from culturing micro-organisms for lysine production. It states that micro-organisms are eliminated from a fermentation broth by separation, filtering, and active carbons as a pre-step, that the broth is concentrated at 20-80° C., and that final products have good free flow property and storage safety by graulating in Filtermat Spray Dry method.
In addition, SU-A-1 735 365 (May 23, 1992) describes a process for the production of animal feed additives with a granular size of 2-4 mm in diameter by mixing fine particles obtained from drying a portion of a culture of micro-organisms with a concentrate of the rest of the culture and making them agglomerate.
In relation to pelletization of L-lysine HCl, EPA 0491638 (Jun. 24, 1992) describes a process for the production of pelletized fine particles in a fluid dryer with a spray method and states that it is advantageous in packing pellets that are 425-1000 μm in diameter. This patent relates to the production of pellets by coating a fluidized bed with solid lysine hydrochloride particles and spraying liquid lysine hydrochloride. Various mechanical stirring machines, for example a drying drum granulator, can be used instead of a fluidized bed.
U.S. Pat. No. 5,431,933 (Jul. 11, 1995) explains a process for the production of pellets that are easy to store and have a lower content of proteins, compared to the feeds produced from a fermentation broth. It is stated that pellets can be directly obtained from drying a fermentation broth together with already separated biomass in a spray method. While the document states that the method yields more than 40% of amino acid contents, it is inadequate to produce this kind of fermentation broth on an industrial scale. The bulk density of the product is even as low as 500-530 kg/m3, as seen in embodiments.
Furthermore, the patent sets the protein content to be less than 10% by weight in order to prevent environmental pollution, and it needs to separate biomass from the fermentation broth. It is stated in Feed Magazine 1/91 which is published before this patent that a decrease in the protein content in feeds reduces environmental pollution.
U.S. Pat. No. 5,622,710 (Apr. 22, 1997) relates to a process for the production of animal feed additives using a fermentation broth without byproducts that cause problems. In this method, fine particles produced in the first step are used to make a final product by a pelletizing process. Products made by this method of the patent have a bulk density of at least 550 kg/m3, more than 33% of the amino acids content, a low hygroscopicity and viscosity. Products with an amino acid content of 40˜90% can be made with this method. In particular, a fermentation broth is prepared by culturing bacteria under sugar-limiting conditions in which the assimilable sugar concentration is kept or decreased below 0.3% by weight, fine particles in a form of powder of which 70% by weight have a granular size of at most 100 μm are obtained by drying the broth in a spray method, then pellets are produced by mixing the particles strongly with a selected binder from a mixture of water and the fermentation broth. 90%, by weight, of the produced pellets have a size of less than 1 mm, and 10%, by weight, of the pellets are less than 100 μm in size.
The drying-pelletizing process of this patent comprises a step of obtaining and spray-drying 70% of fine particles less than 100 μm in size and another step of forming pellets from fine particles by adding water or a fermentation broth as a binder.
U.S. Pat. No. 5,840,358 (Nov. 24, 1998), relates to a process for the production by pelletizing, compacting and drying a concentrated fermentation broth using a pellet dryer as a one-step process. In the method of the patent, products are obtained directly from amino acid fermentation broth in one step of successive processes. In the method, however, additional energy is needed for mechanical devices inside the granulator for the compacting process.
In relation to a process for maintaining a uniform level of lysine, U.S. Pat. No. 5,990,350 (Nov. 23, 1999) and U.S. Pat. No. 6,017,555 (Jan. 25, 2000) describe a process for the production of a lysine product by concentrating a fermentation broth in which biomass is separated, mixing the broth with refined lysine, and adjusting the lysine content to be 35-76%. In the methods, the ratio between a concentrate of the fermentation broth and the refined product must be 2:3 in order to produce a product with at least 55% lysine content.
The discussion in this section is to provide information about related technology and does not constitute an admission of prior art.